156 PROF. OWEN ON NEW AND RARE CEPHALOPODA. 
the great Squid when he applied the name “ Banksii” to a small African hook-armed 
species, which, in 1817, he deemed identical with the larger one of the Pacific Ocean. 
M. @’Orbigny limits his notice of this truly remarkable Cephalopod to the following 
passage :—“ On ne connait de cette espéce qu'une partie d’un bras sessile gigantesque, 
couvert de crochets sur toute sa longueur. Ce caractére étant celui des Enoploteuthis, 
je Vai placé dans ce genre. Je dois 4 l’obligeance de M. Richard Owen un beau dessin 
de ce bras déposé au Musée du Collége des Chirurgiens de Londres.”—Op. cit. p. 339 
(1848). The drawing was a copy of that (Pl. XXXII. fig. 1) which accompanies the 
present paper. My esteemed correspondent and fellow-labourer made no use of it for 
his great work. 
Cephalopods remarkable for large Size. 
Genus PLEctoteutHis!, Owen. 
Species PLECTOTEUTHIS GRANDIS, Owen. 
It has been shown (p. 144) that the side of the arm opposite the acetabuliferous 
tract is longitudinally and mesially ridged, and there more or less produced, in certain 
Squids (Loliginidz) ; but in the British Museum is preserved one of the eight ordinary 
arms of a Cephalopod which, from the characters of the cups (Pl. XXXV. fig. 2), is 
referable to the genus Ommastrephes, @Orb., but which supports them on a relatively 
broader flattened tract (ib. ib. a), and presents on the opposite or dorsal side (Pl. XXXIV. 
fig. 2) a similar flattened tract, a, from each margin of which a fold of the integument, 
6, is produced, of varying breadth. A transverse section of the arm consequently gives 
a quadrate instead of triangular form, in this respect repeating the character shown in 
Loligopsis ocellata. 
The cups or suckers are arranged in a double alternate row along their tract, the 
margins of which are produced into a well-defined fold or thin seam (P]. XXXV. fig. 2, 
c, ¢), but of minor breadth than the dorsal folds. This plicatile condition of the 
ordinary arms has suggested the generic name. 
The length of this arm, which has been amputated at or near its base, is not less 
than 9 feet; the diameter of the amputated base from within outwards is 4 inches; 
the same from side to side is 3 inches; the total circumference is 1 foot. At this basal 
part of the arm (Pl. XXXV. fig. 1) the acetabula have not begun to be developed; it 
would seem to correspond to the non-acetabular tract extending, in most Loliginide, a 
short way from the outer lip. Here, in Plectoteuthis, the folds are restricted to the 
dorsal pair (ib. fig. 1, 4, 6), but they do not exceed an inch in breadth. The opposite 
surface, @, a, is convex across: this convexity broadens into flatness as the arm extends 
and begins to develop itscups. The circumference, taken midway between the two ends 
of the arm, is 9 inches. The breadth of the acetabuliferous tract at 6 inches from the 
amputated end is 53 inches with the marginal folds outstretched; the interspaces 
* Gr. m)exros, folded, revOis, Squid. 
